AA exhaust on a 335

Pseudo Nim · 08-14-2010, 09:12 AM

Hi all,

So a friend of mine has just installed an AA exhaust on his 335, connected to a set of VK downpipes, and he can't figure out if he likes the new noise or not. I'm curious if anybody has a somewhat similar setup. The reason for his incertitude is this: around 2,000rpm there is pretty serious drone, and around 3,000rpm there is a huge spike in noise. So basically, the noise curve goes like this:

0 rpm ---> rising --> rising --> DRONE DRONE DRONE through 2,000rpm --> a bit better at 2,500 ---> HUGE SPIKE at 3,000rpm ---> dropoff and a smooth increase in sound all the way through 7k.

Cruising on the highway @ 110 KM/h (around 65 mph) it's most interesting how in "D" (i.e. 6th) there is HUGE drone, but if you shift to DS and it downshifts to 5, the rpms go to 2,500 (right in between) and there is blissful silence in the car.

Very weird. Is this how this exhaust acts, or is there a leak somewhere in the exhaust? Any thoughts? I would've thought there's some kind of a uniform noise curve, but looks like not. He's thinking of going back to the stock exhaust, heheh.

Thanks!

JoosyJoos · 08-14-2010, 10:10 AM

I have the active exhaust on my car... no downpipes though. It is somewhat true that there is a change in the "noise curve" right around 2000rpm when the turbos go to full spool. I don't notice any drone though. I have had problems with the back middle section (I have a coupe) vibrating right around 1800rpm which I solved by putting a tennis ball and a Tshirt into the compartment. I'd be interested in hearing some more opinions about this since I'm thinking about buying the AA downpipes in the next few months.

Pseudo Nim · 08-14-2010, 10:18 AM

Quote:

Originally Posted by JoosyJoos

I have the active exhaust on my car... no downpipes though. It is somewhat true that there is a change in the "noise curve" right around 2000rpm when the turbos go to full spool. I don't notice any drone though. I have had problems with the back middle section (I have a coupe) vibrating right around 1800rpm which I solved by putting a tennis ball and a Tshirt into the compartment. I'd be interested in hearing some more opinions about this since I'm thinking about buying the AA downpipes in the next few months.

ahem.... could you elaborate on that

re: 2,000 rpm... that's kind of weird. that's where he has the drone... and the noise curve changes around 3,000, but that doesn't make sense as the turbos should already have spooled up by then.

when you cruise at 65mph in 6th, you don't have any drone issues?

TwinTurboXI · 08-14-2010, 11:20 AM

You guys should research vibrant resonators.... I'll be getting them for my car in a day or 2, My magnaflow drowns like a biatch.

Pseudo Nim · 08-14-2010, 11:44 AM

Quote:

Originally Posted by TwinTurboXI

You guys should research vibrant resonators.... I'll be getting them for my car in a day or 2, My magnaflow drowns like a biatch.

details? Are you saying those cancel out the drone? WANT.

JoosyJoos · 08-14-2010, 04:27 PM

Just to elaborate a bit on my issue. The middle compartment of the dash would make a little rattle every time I hit 2000rpm approximately or when i was cruising in 5th or 6th around there. It was really obnoxious and I thought it was "drone" at first. Turns out it was just the plastic middle compartment vibrating once I hit that rpm range. So for the ash tray compartment I stuffed a tennis ball in it... it closes still so you don't ever see it. Then for the middle tray part I stuff an old T shirt in it. The part that rattles is actually the sliding tray and occasionally I have to rearrange the shirt so it doesnt rattle. It's a little ghetto but no one ever sits in my backseat so it doesnt matter to me. You could always just take it out though.

cn555ic · 08-14-2010, 05:24 PM

What your describing in the change of exhaust note is rasp. I had the same problem when I went catless. To eliminate that change in exhaust with sudden throttle modulation get yourself some resonators, specifically Vibrant Performance #1792 resonators. Have an exhaust shop weld them some where along the midpipes. Once you have them installed, the exhaust will be music to your ears without that dreadful change in exhaust tone(rasp). The exhaust tone after I added the resonators became uniform regardless of what rpms the car was at. Look up my thread about Vibrant resonators. Do a search

cn555ic · 08-14-2010, 05:31 PM

One more thing to add. After installing the resonators the exhaust note sounded so much better than it did before I even installed the catless dps to begin with. It's weird how resonators with it ballast can cancell out noise wavelengths like that. They really work and the construction of it looks so simple!!!

bolty · 08-14-2010, 10:01 PM

Is that drone more of a loud "honking" sound?

I have the same sort of problem and I suspect its a problem with vanos.

My exhaust note has always been funky ever since I installed it but it got drastically worse after after a lapping day, when I was able to trigger a vanos code. I have yet to get it fixed.

If you give it a quick hit of gas while its droning, does it immediately go away?

08-14-2010, 09:12 AM	#1
Pseudo Nim twinborific 121 Rep 4,836 Posts Drives: fast, sometimes slow Join Date: Nov 2008 Location: i am a citizen of the world iTrader: (9)	AA exhaust on a 335 - sound/drone, etc Hi all, So a friend of mine has just installed an AA exhaust on his 335, connected to a set of VK downpipes, and he can't figure out if he likes the new noise or not. I'm curious if anybody has a somewhat similar setup. The reason for his incertitude is this: around 2,000rpm there is pretty serious drone, and around 3,000rpm there is a huge spike in noise. So basically, the noise curve goes like this: 0 rpm ---> rising --> rising --> DRONE DRONE DRONE through 2,000rpm --> a bit better at 2,500 ---> HUGE SPIKE at 3,000rpm ---> dropoff and a smooth increase in sound all the way through 7k. Cruising on the highway @ 110 KM/h (around 65 mph) it's most interesting how in "D" (i.e. 6th) there is HUGE drone, but if you shift to DS and it downshifts to 5, the rpms go to 2,500 (right in between) and there is blissful silence in the car. Very weird. Is this how this exhaust acts, or is there a leak somewhere in the exhaust? Any thoughts? I would've thought there's some kind of a uniform noise curve, but looks like not. He's thinking of going back to the stock exhaust, heheh. Thanks! __________________ Doko ni itemo, hito wa tsunagatte iru...
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08-14-2010, 10:10 AM	#2
JoosyJoos Major 118 Rep 1,347 Posts Drives: 2011 335d Join Date: Apr 2007 Location: Atlanta, GA iTrader: (1) Garage List 2008 BMW 335i [0.00]	I have the active exhaust on my car... no downpipes though. It is somewhat true that there is a change in the "noise curve" right around 2000rpm when the turbos go to full spool. I don't notice any drone though. I have had problems with the back middle section (I have a coupe) vibrating right around 1800rpm which I solved by putting a tennis ball and a Tshirt into the compartment. I'd be interested in hearing some more opinions about this since I'm thinking about buying the AA downpipes in the next few months. __________________ 1997 M3 Coupe - BMWCCA I-Prepared #22 2006 M Roadster - 23,000 miles and slowly counting
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08-14-2010, 11:20 AM	#4
TwinTurboXI Lieutenant Colonel 165 Rep 1,523 Posts Drives: 2011 135i Join Date: Mar 2008 Location: . iTrader: (12)	You guys should research vibrant resonators.... I'll be getting them for my car in a day or 2, My magnaflow drowns like a biatch.
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08-14-2010, 04:27 PM	#6
JoosyJoos Major 118 Rep 1,347 Posts Drives: 2011 335d Join Date: Apr 2007 Location: Atlanta, GA iTrader: (1) Garage List 2008 BMW 335i [0.00]	Just to elaborate a bit on my issue. The middle compartment of the dash would make a little rattle every time I hit 2000rpm approximately or when i was cruising in 5th or 6th around there. It was really obnoxious and I thought it was "drone" at first. Turns out it was just the plastic middle compartment vibrating once I hit that rpm range. So for the ash tray compartment I stuffed a tennis ball in it... it closes still so you don't ever see it. Then for the middle tray part I stuff an old T shirt in it. The part that rattles is actually the sliding tray and occasionally I have to rearrange the shirt so it doesnt rattle. It's a little ghetto but no one ever sits in my backseat so it doesnt matter to me. You could always just take it out though. __________________ 1997 M3 Coupe - BMWCCA I-Prepared #22 2006 M Roadster - 23,000 miles and slowly counting
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08-14-2010, 05:24 PM	#7
cn555ic 485 Rep 18,331 Posts Drives: 335i Join Date: Jun 2007 Location: US iTrader: (6)	What your describing in the change of exhaust note is rasp. I had the same problem when I went catless. To eliminate that change in exhaust with sudden throttle modulation get yourself some resonators, specifically Vibrant Performance #1792 resonators. Have an exhaust shop weld them some where along the midpipes. Once you have them installed, the exhaust will be music to your ears without that dreadful change in exhaust tone(rasp). The exhaust tone after I added the resonators became uniform regardless of what rpms the car was at. Look up my thread about Vibrant resonators. Do a search
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08-14-2010, 05:31 PM	#8
cn555ic 485 Rep 18,331 Posts Drives: 335i Join Date: Jun 2007 Location: US iTrader: (6)	One more thing to add. After installing the resonators the exhaust note sounded so much better than it did before I even installed the catless dps to begin with. It's weird how resonators with it ballast can cancell out noise wavelengths like that. They really work and the construction of it looks so simple!!!
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08-14-2010, 10:01 PM	#9
bolty /r/trees 53 Rep 875 Posts Drives: 08 e92 335xi Join Date: May 2008 Location: Ontario, Canada iTrader: (3)	Is that drone more of a loud "honking" sound? I have the same sort of problem and I suspect its a problem with vanos. My exhaust note has always been funky ever since I installed it but it got drastically worse after after a lapping day, when I was able to trigger a vanos code. I have yet to get it fixed. If you give it a quick hit of gas while its droning, does it immediately go away?
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